Particle Shape Measurement Using X-ray Micro Computed Tomography

Abstract

Particle shape is one of the important particle properties, but most particle shape indices are obtained from 2-dimensional projected particle images. Recently, X-ray micro computed tomography was developed and applied to the observation of powder packing structure. We utilized X-ray micro CT Scan for 3-dimensional particle shape measurements including holes, concave surfaces and internal voids. The volume and surface area of a particle can be calculated by integrating the cross sectional area and the perimeter of particle images using X-ray micro CT. Based on our experimental results, the surface area and volume of a particle larger than 60-100μm can be measured with a high degree of accuracy. Wadell's sphericity and circularity are calculated from the surface area and the volume of test particles and compared to each other. As a result, the values of Wadell's sphericity of tablet, hollow particle, cubic and hollow cylinder are not equal to the circularities but they agree for spherical particle. This suggests that 3-dimensional measurements are necessary in the shape analysis for non-spherical particles.